Sounding like a bird, looking like Tom (7)

I believe the answer is:

peeping

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'looking like tom' is the definition.
'peeping' can be an answer for 'looking' (peeping is a kind of looking). I'm not certain of the 'like tom' bit.

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for peeping that I've seen before include "Looking furtively" , ". . . . . . . Tom, furtive observer" .)

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