Animal is generally undernourished, and needing affection primarily (6)
I believe the answer is:
iguana
'animal' is the definition.
(I've seen this before)
'is generally undernourished and needing affection primarily' is the wordplay.
'primarily' suggests taking the first letters.
The first letters of 'is generally undernourished and needing affection' is 'IGUANA'.
(Other definitions for iguana that I've seen before include "Large crested lizard" , "Large tree-climbing specimen of 5 down in tropical America" , "Large lizard of tropical Amercia" , "cold-blooded customer!" , "Type of lizard" .)