Waver like an ass, swapping new for very old moggy (10)
I believe the answer is:
equivocate
'waver' is the definition.
(thesaurus)
'an ass swapping new for very old moggy' is the wordplay.
I cannot really understand how this works, but
'an' could be 'i' (Roman numeral for one) and 'i' is located in the answer.
'very' could be 'v' (abbreviation) and 'v' is located in the answer.
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is present in the answer.
'moggy' could be 'cat' (I've seen this before) and 'cat' is located in the answer.
This explanation may well be incorrect...
'like' acts as a link.
(Other definitions for equivocate that I've seen before include "Beat about the bush" , "Use evasive language" .)