Reserve team, lower (7)
I believe the answer is:
subside
'lower' is the definition.
(thesaurus)
'reserve team' is the wordplay.
'reserve' becomes 'sub' (I've seen this in other clues).
'team' becomes 'side' (both can mean a sports team).
'sub'+'side'='SUBSIDE'
(Other definitions for subside that I've seen before include "Sink to a lower level" , "Abate" , "Go down in level" , "Wane" , "(Flood) go down" .)