Military men carrying a pole for rowing (3)
I believe the answer is:
oar
'pole for rowing' is the definition.
(rowers use oars)
'military men carrying a' is the wordplay.
'military men' becomes 'OR' (Other Ranks - low-ranking soldiers).
'carrying' indicates putting letters inside.
'or' enclosing 'a' is 'OAR'.
(Other definitions for oar that I've seen before include "I'm involved in row" , "spoon?" , "Bladed implement" , "Use it to move a boat" , "Rowing device" .)