In a BBC One show Would I Lie To You the host says "Gary […] has had to endure a dreadful five minutes." (video on Youtube).
I'm curious about the indefinite article, since I've never seen it used in this situation where it clearly refers to the plural of five minutes, and not, for example, a five minute walk. This usage of an a contradicts what I've been taught (in my learner's book the sentence would go "Gary has had to endure dreadful five minutes").
The only thing I can think of is that the dreadful five minutes itself is a description of a singular event/entity, in which case I'd be happy for a name or designation of this language construct (and perhaps even some further examples of it).
Best Answer
in this five minutes has become a single item a single collection of minutes. A single dreadful block of five minutes.
Here are more examples
A collection of painted blue houses
A miserable 30 minutes of rain.
A [descriptive word] [time period] rest of sentence.