Take stock of regulation covering terms of onerous contract (6)
I believe the answer is:
rustle
'take stock' is the definition.
'rustle' can be an answer for 'take' (thesaurus). I'm unsure of the 'stock' bit.
'regulation covering terms of onerous contract' is the wordplay.
'regulation' becomes 'rule' (synonyms).
'covering' means one lot of letters goes inside another.
'terms of onerous contract' becomes 'st' (I can't explain this - if you can you should give a lot more credence to this answer).
'rule' placed around 'st' is 'RUSTLE'.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for rustle that I've seen before include "Steal (cattle, etc)" , "Steal stock" , "Low sound of rubbing" , "Swish - lustre (anag)" , "Steal ((eg, cattle)" .)