Sort of rock site is more rugged (8)

I believe the answer is:

stockier

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

'more rugged' is the definition.
Both the answer and definition are comparative adjectives. Maybe you can see an association between them that I can't see?

'sort of rock site' is the wordplay.
'sort of' indicates an anagram.
'rock'+'site'='rocksite'
'rocksite' anagrammed gives 'STOCKIER'.

'is' is the link.

Can you help me to learn more?

(Other definitions for stockier that I've seen before include "more sturdy?" , "having more beef" , "squatter?" .)

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

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