Gertrude introducing Lawrence to lust? (5)
I believe the answer is:
stein
'gertrude' is the definition.
(I've seen this in another clue)
'introducing lawrence to lust?' is the wordplay.
'introducing' means one lot of letters goes inside another (some letters introduced or inserted into others).
'lawrence' becomes 'TE' (initials of TE Lawrence aka Lawrence of Arabia).
'to lust?' becomes 'sin' (lust is a kind of sin).
'te' placed inside 'sin' is 'STEIN'.
(Other definitions for stein that I've seen before include "Earthenware beer jug" , "Gertrude __, avant-garde US author, d. 1946" , "Inset (anag.)" , "Beer-mug" , "Glass" .)