Senior lawyer on at the end of Prime Time (3)

I believe the answer is:

age

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'time' is the definition.
(I've seen this before)

'senior lawyer on at the end of prime' is the wordplay.
'senior lawyer' becomes 'ag' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'on' is a charade indicator (letters next to each other).
'at the end of' indicates one should take the final letters.
The final letter of 'prime' is 'e'.
'ag'+'e'='AGE'

Can you help me to learn more?

(Other definitions for age that I've seen before include "16/18 [INDUSTRIAL REVOLUTION]" , "Get old" , "How long something has existed" , "Mature, grow in years" , "Years lived so far" .)

I've seen this clue in the Irish Times and the Irish Times (Crosaire).

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