Working across part of garden without a pick (6)
I believe the answer is:
option
'pick' is the definition.
(thesaurus)
'working across part of garden without a' is the wordplay.
'working' becomes 'on' (**).
'across' means one lot of letters goes inside another.
'part of garden' becomes 'patio' ('patio' is part of 'garden').
'without' is a deletion indicator.
'patio' with 'a' removed is 'ptio'.
'on' placed around 'ptio' is 'OPTION'.
(Other definitions for option that I've seen before include "Altenative choice" , "Right to choose" , "Choice, selection" , "Alternative for choice" , "Thing that may be chosen" .)