Becoming more inclined to convert 50% of petrol engines (10)

I believe the answer is:

steepening

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'becoming more inclined' is the definition.
I can't tell whether this defines the answer.

'convert 50% of petrol engines' is the wordplay.
'convert' indicates an anagram (I've seen this in other clues).
'50% of' suggests halving the letters.
'petrol' halved is 'pet'.
'pet'+'engines'='petengines'
'petengines' is an anagram of 'STEEPENING'.

'to' acts as a link.

Can you help me to learn more?

I've seen this clue in The Independent.

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