Store needs time to fatten pig (4)
I believe the answer is:
stow
'store' is the definition.
(synonyms)
'time to fatten pig' is the wordplay.
'time' becomes 't' (abbreviation).
'to fatten' means one lot of letters goes inside another (inserted letters make the word fatter).
'pig' becomes 'sow' (I've seen this before).
't' put inside 'sow' is 'STOW'.
'needs' is the link.
(Other definitions for stow that I've seen before include "Deposit" , "Pack tightly" , "Keep under hatches" , "Author, -- Asimov" , "Put under the hatches" .)