He has a title within his grasp (6)
I believe the answer is:
holder
'he has a title within his' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'grasp' is the wordplay.
I cannot quite see how this works, but
'grasp' could be 'hold' (synonyms) and 'hold' is located in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for holder that I've seen before include "Keeper; container" , "Something which grasps" , "Occupant" , "retainer" , "Noddy" .)