Speak highly of them, though they lost capital, and give them an increase? (5)
I believe the answer is:
raise
'an increase?' is the definition.
(raise can mean to increase or put up)
'speak highly of them though they lost capital and give them' is the wordplay.
I cannot really see how this works, but
'capital' could be 'ai' (resembles 'A1', old-fashioned term for excellent) and 'ai' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for raise that I've seen before include "Make greater" , "Advance" , "Bring up; levy" , "Haul up" , "Contact" .)