From casual perusal, telescope finally picked out a star (6)

I believe the answer is:

pulsar

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

'star' is the definition.
(I know that pulsar is a type of neutron star)

I don't understand the remainder of the clue.

(Other definitions for pulsar that I've seen before include "Regularly radiating stellar object" , "A source of space of radio signals" , "Rapidly rotating star, emitting electromagnetic waves very quickly" , "Radio-emitting star" , "Star producing radio waves" .)

I've seen this clue in The Guardian.

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