Prefer to put back sandwiches containing pork, perhaps (4)
I believe the answer is:
tref
'pork perhaps' is the definition.
I can't tell whether this defines the answer.
'prefer to put back sandwiches' is the wordplay.
'sandwiches' says the answer is hidden in the clue (the answer is sandwiched in by the clue).
'put back' says the letters should be written in reverse.
'fert' is hidden within 'prefer to'.
'fert' reversed gives 'TREF'.
'containing' is the link.
Can you help me to learn more?
(Other definitions for tref that I've seen before include "not kosher" , "Not conforming to certain laws" .)