Biplane agent repaired (mechanical reparation) (5,7)

I believe the answer is:

panel beating

I'm a little stuck... Click here to teach me more about this clue!

'mechanical reparation' is the definition.
'panel beating' can be an answer for 'reparation'. I am not certain of the 'mechanical' bit.

'biplane agent repaired' is the wordplay.
'repaired' indicates anagramming the letters.
'biplane'+'agent'='biplaneagent'
'biplaneagent' is an anagram of 'PANEL BEATING'.

Can you help me to learn more?

(Other definitions for panel beating that I've seen before include "Metal work's needed" , "Restoring dented car bodywork" .)

I've seen this clue in The Everyman puzzle in The Observer.

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