Outside, a new detective goes astray with commissions (7)
I believe the answer is:
errands
'commissions' is the definition.
(I've seen this before)
'outside a new detective goes astray' is the wordplay.
'outside' indicates putting letters inside (some letters go outside others).
'new detective' becomes 'nd' (this could be a standard abbreviation I've not previously seen).
'goes astray' becomes 'errs' (I've seen this in another clue).
'a'+'nd'='and'
'and' going inside 'errs' is 'ERRANDS'.
'with' acts as a link.
Can you help me to learn more?
(Other definitions for errands that I've seen before include "Small jobs" , "Trips to carry out tasks" , "trips on someone's behalf" , "Short trips to perform commissions" , "Task-oriented trips" .)