Reading Gaol's closure years after it goes over limits of capacity (8)
I believe the answer is:
literacy
'reading' is the definition.
(thesaurus)
'gaol's closure years after it goes over limits of capacity' is the wordplay.
'closure' suggests the final letters (the letter which closes the word).
'years' becomes 'era' (I've seen this in another clue).
'after' means one lot of letters go next to another.
'goes over' means one lot of letters go next to another.
'limits of' means to remove the middle letters.
'capacity' with its centre taken out is 'cy'.
The last letter of 'gaol' is 'l'.
'era' put after 'it' is 'itera'.
'l'+'itera'+'cy'='LITERACY'
(Other definitions for literacy that I've seen before include "Ability to read and write" , "education?" , "The 3 Rs" , "Ability to use language proficiently" , "Writer's skill" .)