Caught erstwhile setter’s fancy (8)
I believe the answer is:
conceive
'fancy' is the definition.
(thesaurus)
'caught erstwhile setter's' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'erstwhile' becomes 'once' ('once' can be a synonym of 'erstwhile').
'setter's' becomes 'ive' (I've seen this in other clues).
'c'+'once'+'ive'='CONCEIVE'
(Other definitions for conceive that I've seen before include "Form thought in the mind - or become pregnant" , "Design" , "Have the idea for" , "Envisage - become pregnant" , "Become pregnant - imagine" .)