We blame knitter for small woolly jumper (3,4)
I believe the answer is:
ewe lamb
'small woolly jumper' is the definition.
'we blame knitter' is the wordplay.
'knitter' is an anagram indicator.
'we'+'blame'='weblame'
'weblame' with letters rearranged gives 'EWE-LAMB'.
'for' is the link.
(Other definitions for ewe lamb that I've seen before include "precious possession" , "Farm occupant" , "Little treasure" , "Web meal (anag.)" , "favourite member of the flock" .)