Rest of weight porky lecturer carries (3-4)
I believe the answer is:
lie-down
'rest' is the definition.
(to lie down is to have a short rest)
'weight porky lecturer carries' is the wordplay.
'weight' becomes 'w' (short for weight).
'porky' becomes 'lie' (I've seen this in other clues).
'lecturer' becomes 'don' (don can mean an academic).
'carries' means one lot of letters goes inside another.
'lie'+'don'='liedon'
'w' put into 'liedon' is 'LIE-DOWN'.
'of' is the link.
(Other definitions for lie-down that I've seen before include "Short rest" , "Rest (with or without sleep)" .)