Sailing ship may have this power source and energy in the supply (9)
I believe the answer is:
mainsheet
'sailing ship may have this power' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'source and energy in the supply' is the wordplay.
'source' becomes 'mains' (I have seen 'source of power' mean 'mains' so perhaps 'source' could also mean 'mains').
'and' says to put letters next to each other.
'energy' becomes 'e' (physics symbol as in E=mca).
'in' indicates putting letters inside.
'supply' indicates an anagram (in a supple way).
'the' is an anagram of 'het'.
'e' going within 'het' is 'heet'.
'mains'+'heet'='MAINSHEET'
Can you help me to learn more?
(Other definitions for mainsheet that I've seen before include "rope found on board" , "Nautical rope" , "Some tackle" , "shipping line" , "front page?" .)