Detective more competent without British dilettante (7)
I believe the answer is:
dabbler
'dilettante' is the definition.
(I know that dilettante can be written as dabbler)
'detective more competent without british' is the wordplay.
'detective' becomes 'd' (this might be a standard abbreviation of which I'm unaware).
'more competent' becomes 'abler' ('able' can be similar in meaning to 'competent').
'without' is an insertion indicator ('without' can be similar in meaning to 'outside').
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'abler' going around 'b' is 'abbler'.
'd'+'abbler'='DABBLER'
Can you help me to learn more?
(Other definitions for dabbler that I've seen before include "Someone with passing interest" , "amateur" , "Dilettante" .)