I learn about a type of equation (6)

I believe the answer is:

linear

'a type of equation' is the definition.

'i learn about' is the wordplay.
'about' is an anagram indicator.
'i'+'learn'='ilearn'
'ilearn' with letters rearranged gives 'LINEAR'.

(Other definitions for linear that I've seen before include "In a straight line" , "Long and narrow, of one dimension" , "Measured lengthwise" , "adopting common narrative style" , "(Of narrative) sequential" .)

I've seen this clue in The Telegraph.

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