I'm after a purpose in life (3)

I believe the answer is:

aim

I'm a little stuck... Click here to teach me more about this clue!

'purpose in life' is the definition.
'aim' can be an answer for 'purpose' (synonyms). I am unsure of the 'in life' bit.

'i'm after a' is the wordplay.
'i'm' becomes 'im' ().
'after' means one lot of letters go next to another.
'im' after 'a' is 'AIM'.

Can you help me to learn more?

(Other definitions for aim that I've seen before include "intent" , "Direct; intention" , "Goal, objective" , "Plan" , "Set sights on, say target" .)

I've seen this clue in The Globe and Mail.

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