Rank motive is not specialised (7,7)

I believe the answer is:

general purpose

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'not specialised' is the definition.
I can't tell whether this defines the answer.

'rank motive' is the wordplay.
'rank' becomes 'general' (I've seen this before).
'motive' becomes 'purpose' (purpose is a kind of motive).
'general'+'purpose'='GENERAL-PURPOSE'

'is' acts as a link.

Can you help me to learn more?

(Other definitions for general purpose that I've seen before include "Having several jobs" , "broadly useful" .)

I've seen this clue in The Daily Express.

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