Labour with dual winch, alternately operated by fluid (9)
I believe the answer is:
hydraulic
'operated by fluid' is the definition.
The answer and definition are not the same part of speech. However, past participle verbs and adjectives can occasionally define each other.
'labour with dual winch alternately' is the wordplay.
'labour with' becomes 'hydra' (I can't explain this - if you can you should give a lot more credence to this answer).
'alternately' indicates alternate letters.
'dual'+'winch'='dualwinch'
The alternate letters of 'dualwinch' are 'ulic'.
'hydra'+'ulic'='HYDRAULIC'
Can you help me to learn more?
(Other definitions for hydraulic that I've seen before include "Sort of brake" , "Relating to liquids under pressure" , "Operated by pressure through pipe by liquid" , "moved under pressure" , "Operated by liquid (water or oil)" .)