Crossword Genius

Amplifier initially made a signal very clipped at both ends (5)

Ross

I believe the answer is:

maser

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

'amplifier' is the definition.
(I know that maser is a type of amplifier)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for maser that I've seen before include "Microwave beam generator" , "Microwave beam producer" .)

I've seen this clue in The Times.
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