Admission made by one catching cold on steamship (6)
I believe the answer is:
access
'admission' is the definition.
(thesaurus)
'one catching cold on steamship' is the wordplay.
'one' becomes 'ace' ('ace' can be a synonym of 'one'**).
'catching' is an insertion indicator.
'cold' becomes 'c' (eg on taps).
'on' is a charade indicator (letters next to each other).
'steamship' becomes 'ss'.
'ace' placed around 'c' is 'acce'.
'acce'+'ss'='ACCESS'
'made by' acts as a link.
(Other definitions for access that I've seen before include "Means or way of gaining entry" , "The right to see, eg, children after divorce" , "Means, or right, of approach" , "Admittance, entree" , "Admission" .)