Look for gold? Favouring muscle when drilling stone (8)
I believe the answer is:
prospect
'look for gold?' is the definition.
'prospect' can be an answer for 'look' (thesaurus). I'm not certain of the 'for gold?' bit.
'favouring muscle when drilling stone' is the wordplay.
'favouring' becomes 'pro' (being in favour of something).
'muscle' becomes 'pec' (pectoral muscle).
'when drilling' means one lot of letters goes inside another.
'stone' becomes 'st' (abbreviation).
'pec' placed within 'st' is 'spect'.
'pro'+'spect'='PROSPECT'
Can you help me to learn more?
(Other definitions for prospect that I've seen before include "Likely customer - search for gold" , "Potential customer" , "Extensive view; search for minerals" , "Survey the outlook" , "Extensive landscape" .)