Guard deployed to trouble spot, perhaps, felt exposed (8)
I believe the answer is:
sentinel
'guard' is the definition.
(sentinel is a kind of guard)
'perhaps felt exposed' is the wordplay.
'perhaps' becomes 'sentin' (I can't explain this - if you can you should give a lot more credence to this answer).
'exposed' says to take the centre (outside letters removed).
The middle of 'felt' is 'el'.
'sentin'+'el'='SENTINEL'
'deployed to trouble spot' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for sentinel that I've seen before include "Look-out, military guard" , "Guardsman" , "Watching guard" , "Watchperson" , "Guard who stands and keeps watch" .)