Cheering arrival outside stronghold (10)
I believe the answer is:
comforting
'cheering' is the definition.
(I know that cheering can be written as comforting)
'arrival outside stronghold' is the wordplay.
'arrival' becomes 'coming' (coming is a kind of arrival).
'outside' means one lot of letters goes inside another (some letters go outside others).
'stronghold' becomes 'fort' (I've seen this in another clue).
'coming' enclosing 'fort' is 'COMFORTING'.
(Other definitions for comforting that I've seen before include "Reassuring" , "Cheering" .)