One making adjustments to a fine pitch? (5)
I believe the answer is:
tuner
'one making adjustments to a fine pitch?' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'one' is the wordplay.
I cannot really understand how this works, but
'one' could be 'un' (northern English dialect form of 'one') and 'un' is found in the answer.
The remaining letters 'ter' 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 tuner that I've seen before include "Adjuster of pianos" , "Radio receiver" , "Radio adjuster" , "Motor specialist" , "Piano adjuster" .)