1a Punch gets supporter to change sides P?E?C?
20d Yarn, we hear, devoid of pity ?R???L argyll possibly but why?
The y may come from:
25a Bird is going to city centre devouring anything - think it's yellow tit or willow tit (owt = anything , it cITy centre)
6d Lying about rock star R?S?I?G must be resting but not sure why?