Pressure on soldier to return swine (3)
I believe the answer is:
pig
'swine' is the definition.
(pig is a kind of swine)
'pressure on soldier to return' is the wordplay.
'pressure' becomes 'p' (abbreviation).
'on' says to put letters next to each other.
'soldier' becomes 'gi' (government issue or general issue**).
'to return' says the letters should be written in reverse.
'gi' written backwards gives 'ig'.
'p'+'ig'='PIG'
(Other definitions for pig that I've seen before include "Eg, sow" , "Greedy person (colloq.)" , "& 16 Animal pen" , "Domestic swine" , "Eat greedily" .)