Dolly's involved in marine insurance (6)
I believe the answer is:
lloyds
'marine insurance' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'dolly's involved' is the wordplay.
'involved' indicates anagramming the letters (involved can mean confusing or complex).
'dollys' with letters rearranged gives 'LLOYDS'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for lloyds that I've seen before include "London insurance agency" , "Clive, Marie, Sian and Harold, perhaps" , "London insurance association" , "Underwriters with "names"" , "Group with black horse" .)