Picture beakers just filled from the tea urn? (7)
I believe the answer is:
mugshot
'picture' is the definition.
(I've seen this before)
'beakers just filled from the tea urn?' is the wordplay.
'beakers' becomes 'mugs'.
'just filled from the tea urn?' becomes 'hot'.
'mugs'+'hot'='MUGSHOT'
(Other definitions for mugshot that I've seen before include "picture" , "Passport photograph?" , "ID photograph (colloq.)" , "Photo of ones face" , "Police snap" .)