Sang and wittered on with Liberal in higher position (7)
I believe the answer is:
blabbed
'sang' is the definition.
('blab' can be a synonym of 'sing')
'with liberal in higher position' is the wordplay.
'with' means one lot of letters goes inside another.
'liberal' becomes 'l' (abbreviation).
'in higher' becomes 'bab' (I can't explain this - if you can you should give a lot more credence to this answer).
'position' becomes 'bed' (bedding is a kind of positioning).
'l' inserted within 'bab' is 'blab'.
'blab'+'bed'='BLABBED'
'and wittered on' acts as a link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for blabbed that I've seen before include "Spilt the beans" , "Talked indiscreetly" , "Let the cat out of the bag" .)