Do you need pluck to play it? (4)
I believe the answer is:
harp
'do you' is the definition.
The definition suggests a singular noun which matches the answer.
'need pluck to play it?' is the wordplay.
'need' becomes 'why' (why is a kind of need).
'pluck' means to look at the middle letters (I've seen 'plucked' mean this (external letters removed as in plucking feathers)).
'to play it?' becomes 'arp' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The middle letter of 'why' is 'h'.
'h'+'arp'='HARP'
Can you help me to learn more?
(Other definitions for harp that I've seen before include "''The ... that once through Tara's halls'' (4)" , "Heavenly instrument?" , "semitone higher, abandoning intro" , "David's instrument" , "Lyre" .)