Reimburse troops to some extent (7)
I believe the answer is:
requite
'reimburse' is the definition.
(thesaurus)
'troops to some extent' is the wordplay.
'troops' becomes 'RE' (Royal Engineers army regiment).
'to' says to put letters next to each other.
'some extent' becomes 'quite' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
're'+'quite'='REQUITE'
Can you help me to learn more?
(Other definitions for requite that I've seen before include "Appropriately, give back" , "Make return" , "Quieter (anag.)" .)