Less faultless service outside the shopping precinct (7)
I believe the answer is:
smaller
'less' is the definition.
(thesaurus)
'faultless service outside the shopping precinct' is the wordplay.
'faultless service' becomes 'ser' (I can't justify this - if you can you should give a lot more credence to this answer).
'outside' is an insertion indicator (some letters go outside others).
'the shopping precinct' becomes 'mall' (shopping mall).
'ser' going around 'mall' is 'SMALLER'.
Can you help me to learn more?
(Other definitions for smaller that I've seen before include "Not as big as" , "Less extensive" , "More diminutive" , "Sell ram (anag.)" .)