Spring on the banks of the Lee is cheap (4)
I believe the answer is:
leap
'spring' is the definition.
('leap' can be a synonym of 'spring')
'on the banks of the lee is cheap' is the wordplay.
'on' is a charade indicator (letters next to each other).
'the banks of' suggests removing the centre (the banks are the sides of the word).
'is cheap' becomes 'ap' (I can't justify this - if you can you should give a lot more credence to this answer).
'lee' with its middle taken out is 'le'.
'le' next to 'ap' is 'LEAP'.
Can you help me to learn more?
(Other definitions for leap that I've seen before include "some years?" , "Sudden bound" , "Jump a long way" , "Spring suddenly" , "Jump suddenly" .)