Saga Cryptic July 2019

[zoomer]

7D Nag, horse at extremes of exhaustion has to stumble. (7) H*N*E*K. I feel it's probably HENPECK but I can't parse it.
Any explanation would be most welcome. T.I.A.

[fiction-factory]

I can see H for Horse and EN from extreme letters of ExhaustioN but I can't get heck from, presumably, stumble

[Toorak]

H(orse) e(xhaustio)n peck (stumble)

[Toorak]

Peck is a synonym of stumble

[zoomer]

Thanks fiction-factory - at least that's part of it.

[fiction-factory]

Oops. meant peck not heck- not seeing the peck/stumble link yet though

[zoomer]

Many thanks Toorak. Great stuff.

[Toorak]

peck3
/pɛk/
verb
verb: peck; 3rd person present: pecks; past tense: pecked; past participle: pecked; gerund or present participle: pecking
(of a horse) pitch forward or stumble as a result of striking the ground with the front rather than the flat of the hoof.
"her father's horse had pecked slightly on landing"