Synecdoche is the use of a deliberate confusion of scale, in which a poet refers to one thing in terms of a part of it - or in terms of what it is a part of. So a person could be "a sympathetic ear", or the person who was actually speaking when the news reports that "the government said today...". The person is neither just an ear nor the whole government, but using synecdoche to suggest that s/he is heightens that role.

The mysterious arsonist in 'Incident on a Holiday', by Alan Brownjohn, is just "unpoliced fingers", a synecdoche that maintains the mystery with this extreme close-up.