Imagine troops breaching barrier (5)
I believe the answer is:
dream
'imagine' is the definition.
(dreaming is a kind of imagining)
'troops breaching barrier' is the wordplay.
I cannot really see how this works, but
'troops' could be 're' (I've seen this in other clues) and 're' is found in the answer.
'barrier' could be 'dam' (dam is a kind of barrier) and 'dam' is located in the leftover letters.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for dream that I've seen before include "Cherished hope; fantasy" , "Night-time fantasy" , "Armed (anag)" , "Think vaguely" , "Vision - very pleasant person" .)