Spectate: old boy to start tennis game? (7)
I believe the answer is:
observe
'spectate' is the definition.
The answer and definition can be both to do with perception as well as being verbs in their base form.
Perhaps you can see a link between them that I don't see?
'old boy to start tennis game?' is the wordplay.
'old boy' becomes 'OB' (abbreviation for a private school 'old boy').
'to start' is a charade indicator (letters next to each other).
'tennis game?' becomes 'serve' (I can't explain this - if you can you should believe this answer much more).
'ob'+'serve'='OBSERVE'
Can you help me to learn more?
(Other definitions for observe that I've seen before include "Keep; notice" , "Notice or conform to, rules say" , "Obverse (anag.)" , "Keep - watch" , "Mark" .)