Warble around water source surging (8)
I believe the answer is:
swelling
'surging' is the definition.
Although both the answer and definition are present participle verbs, I can't see how one could define the other.
'warble around water source' is the wordplay.
'warble' becomes 'sing' (I've seen this before).
'around' means one lot of letters goes inside another.
'water source' becomes 'well' (I've seen this in another clue).
'sing' placed around 'well' is 'SWELLING'.
Can you help me to learn more?
(Other definitions for swelling that I've seen before include "area suffering inflation" , "Nodule" , "Bulge" , "Growth" , "growing" .)