Daily Mail

[corylus]

2 Down: Agency ruins fresh way of thinking over time (15)

I have i?s?r?m?n?a?i??

26 Across: Try cutting tree all back to reveal another one (6)

[dannyk13]

Instrumentation

[dannyk13]

26a. Myrtle

[Sipowicz]

Instrumentality.

[dannyk13]

Thesaurus gives instrumentation as agency

[Sipowicz]

http://www.thefreedictionary.com/instrumentality

[dannyk13]

HI Sipo. It would seem that both might fit but I presume you have the paper?

[Sipowicz]

Danny, the y in myrtle is the y in instrumentality.

[Sipowicz]

Crossed posts, yes Danny.

[dannyk13]

Thanks for that.It is obviously instrumenality

[dannyk13]

Instrumentality even

[frugalfred]

Anag of RUINS round Time followed by thinking = MENTALITY.

[dannyk13]

Yes Fed but definition of mentation is mental activity.

[frugalfred]

Thanks, Danny. I've had a look in Chambers - you're right. Obviously one of those answers that can only be confirmed by cross-check. I see myrtle confirms the "Y".
Cheers.

[Sipowicz]

'Way of thinking' = mentality.

[corylus]

Thanks everybody, bit complicated, no wonder I was stuck! It was myrtle that had me confused, thought 2 D was instrumentation