Suspects put by soldiers in strongholds (8)
I believe the answer is:
redoubts
'strongholds' is the definition.
(I know this)
'suspects put by soldiers' is the wordplay.
'suspects' becomes 'doubts' (doubting is a kind of suspecting).
'put by' is a charade indicator (letters next to each other).
'soldiers' becomes 're' (Royal Engineers).
'doubts' after 're' is 'REDOUBTS'.
'in' is the link.
(Other definitions for redoubts that I've seen before include "Obtrudes into outer fortifications" , "Temporary or supplementary fortifications" , "defences" .)