One made internet difficult, being vague (13)
I believe the answer is:
indeterminate
'vague' is the definition.
(I've seen this before)
'one made internet difficult' is the wordplay.
'one' becomes 'i' (Roman numeral).
'difficult' indicates an anagram.
'made'+'internet'='madeinternet'
'madeinternet' anagrammed gives 'ndeterminate'.
'i'+'ndeterminate'='INDETERMINATE'
'being' acts as a link.
(Other definitions for indeterminate that I've seen before include "Unspecified" , "Not precisely fixed" , "not exactly fixed" , "uncertain result?" , "Vague - unsettled" .)