Periodically need farm to produce cheese (4)
I believe the answer is:
edam
'cheese' is the definition.
(I know that Edam is a type of cheese)
'periodically need farm' is the wordplay.
'periodically' means one should take alternating letters (letters must be selected 'every so often').
'need'+'farm'='needfarm'
The alternate letters of 'needfarm' are 'EDAM'.
'to produce' acts as a link.
(Other definitions for edam that I've seen before include "milk product" , "town in Holland" , "something to have with crackers" , "Cheese made badly" , "Made into a nice cheese" .)