Take careful steps with stunt about to block reasonable location for lighthouse (8,4)

'location for lighthouse' is the definition.
(ref to Robert Southey poem The Inchcape Rock)

'take careful steps with stunt about to block' is the wordplay.
'take careful steps' becomes 'inch'.
'with' says to put letters next to each other.
'stunt' becomes 'caper'.
'about' says the letters should be written backwards.
'to block' becomes 'kco' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'kco' written backwards gives 'ock'.
'inch'+'caper'+'ock'='INCHCAPE ROCK'

'reasonable' is the link.
I am not very happy about this link. It may belong to another bit of the clue.