Group starts to sketch Eiffel Tower (3)
I believe the answer is:
set
'group' is the definition.
(set is a kind of group)
'starts to sketch eiffel tower' is the wordplay.
'starts to' indicates taking the first letters.
The first letters of 'sketch eiffel tower' is 'SET'.
(Other definitions for set that I've seen before include "Harden; fixed; group" , "Major division of tennis match" , "Where they're filming" , "Group; hard" , "Solidify; group" .)