Attention needed after weight put on (4)
I believe the answer is:
wear
'put on' is the definition.
(to put something on is to wear it)
'attention needed after weight' is the wordplay.
'attention' becomes 'ear' (having someone's ear is having their attention).
'needed after' says to put letters next to each other.
'weight' becomes 'w' (short for weight).
'ear' put after 'w' is 'WEAR'.
(Other definitions for wear that I've seen before include "brook" , "(Put on) clothing" , "Be clothed in" , "Tolerate" , "Waste away" .)