In the middle of Warsaw, following beams (7)
I believe the answer is:
rafters
'beams' is the definition.
(I know this)
'in the middle of warsaw following' is the wordplay.
'in the' is an insertion indicator.
'middle of' says to take the centre.
'following' becomes 'after' (I've seen this in another clue).
The middle letters of 'warsaw' are 'rs'.
'rs' going around 'after' is 'RAFTERS'.
(Other definitions for rafters that I've seen before include "Internal roof beams" , "Roof supports" .)