Warm-hearted little chap, wonderfully watchful (5)

I believe the answer is:

argus

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'wonderfully watchful' is the definition.
I can't tell whether this defines the answer.

'warm-hearted little chap' is the wordplay.
'hearted' means to look at the middle letters.
'little chap' becomes 'gus' (I am not sure about the 'little' bit.**).
The centre of 'warm' is 'ar'.
'ar'+'gus'='ARGUS'

Can you help me to learn more?

(Other definitions for argus that I've seen before include "Hundred-eyed giant in mythology" , "Alert watchman" , "Legendary Guardian" , "Small butterfly" , "In Greek myth, a many-eyed monster slain by Hermes" .)

I've seen this clue in the Evening Standard.

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