Hold tightly; that is right to be more tenacious (8)

I believe the answer is:

clingier

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'more tenacious' is the definition.
Both the definition and answer are comparative adjectives.
Maybe they are linked in a way I don't understand?

'hold tightly that is right' is the wordplay.
'hold tightly' becomes 'cling' (I've seen this in another clue).
'that is' becomes 'ie' (abbreviation for id est, 'that is' in Latin).
'right' becomes 'r' (abbreviation).
'cling'+'ie'+'r'='CLINGIER'

'to be' is the link.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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