Digression (7)
'digression' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tangent that I've seen before include "Line that touches curve without crossing it" , "Trig ratio" , "What people often go off at!" , "Line touching curve at one point" , "mostly irrelevant item" .)
'digression' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for aside that I've seen before include "Words spoken apart in an undertone" , "Remark not for hearing" , "Privately, apart" , "Away from main action" , "I.e. sad (anag.)" .)
'digression' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for sidetrack that I've seen before include "Divert" , "Provide diversion" , "lead away" , "Bit of railway" , "draw away" .)