Polish troops occupying base close to Stargard (5)
I believe the answer is:
emend
'polish' is the definition.
(I've seen this in another clue)
'troops occupying base close to stargard' is the wordplay.
'troops' becomes 'men' (I've seen this in another clue).
'occupying' is an insertion indicator (inserted letters occupy or enter the word).
'base' becomes 'e' (Euler's number - base of natural logarithms).
'close to' indicates one should take the final letters (the close/ending of).
The final letter of 'stargard' is 'd'.
'e'+'d'='ed'
'men' put into 'ed' is 'EMEND'.
(Other definitions for emend that I've seen before include "Make improvements to (text)" , "would appear better" , "do editorial work" , "Alter to improve (text)" , "Make improvements or corrections" .)