Plump for new shelf with sturdy back (6)
I believe the answer is:
fleshy
'plump' is the definition.
(I've seen this in another clue)
'new shelf with sturdy back' is the wordplay.
'new' indicates anagramming the letters.
'with' means one lot of letters go next to another.
'back' indicates one should take the final letters.
The last letter of 'sturdy' is 'y'.
'shelf' anagrammed gives 'flesh'.
'flesh'+'y'='FLESHY'
'for' is the link.
(Other definitions for fleshy that I've seen before include "Fat" , "voluptuous!" , "Plump; soft and thick" , "Sarcoid" , "Pulpy" .)