Lowliness of press employee given directions in Mass, say (12)

'lowliness' is the definition.
(thesaurus)

'press employee given directions in mass say' is the wordplay.
'press employee' becomes 'sub' (subeditor).
'given' says to put letters next to each other.
'directions' becomes 'en' (east and north).
'in' indicates putting letters inside.
'mass say' becomes 'service' (Mass is a type of church service).
'en' inserted inside 'service' is 'servience'.
'sub'+'servience'='SUBSERVIENCE'

'of' acts as a link.