Add to supply of gnu meat (7)
I believe the answer is:
augment
'add to' is the definition.
(I've seen this before)
'of gnu meat' is the wordplay.
'of' indicates anagramming the letters (the answer comes from or 'of' the letters).
'gnu'+'meat'='gnumeat'
'gnumeat' with letters rearranged gives 'AUGMENT'.
'supply' acts as a link.
(Other definitions for augment that I've seen before include "get longer" , "Increase number of" , "Enlarge or increase" , "boost" , "Add to, increase" .)