What tennis player might do after a fault -- hold back (7)
I believe the answer is:
reserve
This clue could be a double definition.
'what tennis player might do after a fault' is the first definition.
The definition suggests a singular noun which matches the answer.
'hold back' is the second definition.
(thesaurus)
Can you help me to learn more?
(Other definitions for reserve that I've seen before include "Reticence" , "cool" , "Book - spare player" , "Lack of openness" , "not in the front line" .)