Terms in list are endless in magazine (8)
I believe the answer is:
glossary
'terms in list' is the definition.
'glossary' can be an answer for 'list' (I have seen 'Explanatory list ' mean 'glossary' so perhaps 'list' could also mean 'glossary'). I'm unsure of the 'terms in' bit.
'are endless in magazine' is the wordplay.
'endless' means to remove the last letter.
'in' means one lot of letters goes inside another.
'magazine' becomes 'glossy' (I've seen this before).
'are' with its last letter taken off is 'ar'.
'ar' inserted inside 'glossy' is 'GLOSSARY'.
Can you help me to learn more?
(Other definitions for glossary that I've seen before include "List of technical words with definitions" , "A grossly distorted list of special words and definitions" , "set of explanations" , "List of words pertaining to a subject" , "List of terms text uses" .)