Guys possibly helping to make Europe secure (5)
I believe the answer is:
ropes
'guys' is the definition.
(I've seen this before)
'helping to make europe secure' is the wordplay.
'helping to make' indicates a hidden word.
'ROPES' is hidden in the letters of 'europe secure'.
'possibly' is the link.
(Other definitions for ropes that I've seen before include "known by clued-up workers?" , "They're known by experts" , "pearls or > onions" , "known to be adept?" , "Ties" .)