Senior metalworker loses weight (5)
I believe the answer is:
Here is my best explanation:
'senior' is the definition.
(similar in meaning)
'metalworker loses weight' is the wordplay.
'metalworker' becomes 'welder' (I've seen this before).
'loses' is a deletion indicator.
'weight' becomes 'w'.
'welder' with 'w' taken out is 'ELDER'.